There are hydraulic flow control valves which can be adjusted to allow proper flow for a variety of attachments. Such hydraulic flow control valves have been used with the backhoe portion of some backhoe loaders.
Some hydraulic flow control adjustment arrangements are not user friendly and often must take place at a dealer with the use of a flow meter to adjust to the exact flow required. For example, there is a closed-center, pressure-compensated, load-sense, auxiliary flow control valve used with a piston pump. The valve has a spool and an adjustable spool stop to provide any flow setting between 13 gpm (i.e., gallons per minute) and 35 gpm. The adjustment is made using a standard capscrew, but requires use of a flow meter.
Some other hydraulic flow control valves have a rotary knob with discrete flow rate settings, but typically involve switching between different size orifices by rotating the knob to select the proper flow rate setting for the hydraulic attachment. In some examples, an open-center auxiliary flow control valve used with a gear pump has a six-position rotary knob that uses orifices to determine the flow rate to the work port (e.g., 9, 13, 16, 18, 22, 25 gpm). In other examples, a stand-alone auxiliary flow control valve uses a rotary knob with eight flow rate settings that switches between eight different orifice sizes (e.g., 9, 13, 16, 18, 22, 26, 30, 35 gpm).